## The Higgs boson: the final piece the standard model and a powerful tool to search for new physics

The discovery of the SM-like Higgs boson in 2012 was a triumph for both experimental and theoretical particle physics. If the boson is indeed a fundamental scalar, it is the first such particle observed -- perhaps the first of many. Further studies of this boson will address such questions as: Is the Higgs boson a fundamental particle, or a composite particle made from more elementary particles? Is this the only Higgs boson, or do multiple Higgs bosons exist in nature? Are there new particles, perhaps the dark matter particle, that interact not through the SM forces, but through the Higgs boson alone?

The Oxford group played a lead role in the discovery of the Higgs boson using its decays to W-boson pairs (HWW), and more recently performed the first observation of Higgs boson decays to b-quark pairs (Hbb), found the first evidence for Higgs boson decays to muon pairs (Hmumu), and set the best constraints on the coupling of the Higgs boson to charm quarks (Hcc).  The measurements test the predicted relationship between interaction strength and particle mass, and in particular the difference in interaction strength between the fermion generations.

Oxford have also searched for new Higgs bosons decaying to tau-lepton pairs, to Z-boson pairs, and to Higgs-boson pairs. Additionally, Oxford searches for H($$\rightarrow$$bb)H($$\rightarrow$$bb) and H($$\rightarrow$$bb)H($$\rightarrow$$WW) production test the self-coupling of the Higgs boson predicted by the Higgs mechanism.  By the end of the LHC lifetime it may be possible to find evidence for the pair-production of Higgs bosons.

Oxford offers research opportunities for students in these areas in Run 3, as well as new opportunities to probe for matter-antimatter asymmetry in the H$$\rightarrow$$tau-tau decay, and to search for HH in the H($$\rightarrow$$bb)H($$\rightarrow$$tau-tau) channel. Run 3 is expected to produce more than twice the data of Run 2, improving the expected precision and sensitivity to new physics.

Contact: Daniela Bortoletto, Chris Hay, Ian Shipsey

## Current group members

Daniela Bortoletto

Chris Hays

Ian Shipsey

Giacomo Artoni (HZZ and Hmumu)

Elizabeth Schopf (Hbb and Hcc)

Chris Pollard

Maxence Draguet (Hbb, Hcc)

Maria Giovanna Foti (Hbb)

Kla Karava (HWW)

Maria Mironova (Hcc)

Hayden Smith (HWW)

Philipp Windischhofer (Hbb)

Ricardo Wölker (HZZ)

Siyuan Yan (HZZ)

Yingjie Wei (HZZ)